The novel screen system comprises a particular form of roller blind and a pair of guide rails disposed on either side of an aperture to control blind position as it is deployed/retracted to cover/uncover the aperture. The blind fabric has flexible strips on its lateral sides which are trapped within, but free to slide along, a specially shaped groove or keyway in each of the rails. Each flexible strip typically is one half of a zipper, but could be manufactured by moulding a soft or semi-rigid high polymer such as hot-melt synthetic resin or rubber. A roller blind with such flexible strips for engaging corresponding rails is hereinafter referred to as a zip-like screen.
U.S. Pat. No. 4,638,844 discloses an early form of screen system, with a simple bracket for loosely mounting a guide rail. GB 2 235 005 discloses an improved bracket for loosely mounting a guide rail. FIGS. 1A and 1B show existing brackets for loosely mounting a guide rail. The bracket 10 of FIG. 1A is configured to be secured to a surface forming part of the inner periphery of the aperture to be screened, whereas the bracket 20 of FIG. 1B is configured to be secured via an additional flange 22 to a surface extending away from the aperture to be screened. Each bracket 10,20 comprises an aluminium extrusion 30 and a pair of clip-on strips of plastics material 32, which together define a channel 33 for receiving a rail 34 (shown in dotted lines). The rail 34 is supported within the channel 33 by pairs of resilient foam strips 36 which provide some flexibility and allow the depth D of the rail 34 within the channel 33 to vary if required.
A blind system with a zip-like screen is only able to control blind position as it is deployed and retracted if the guide rails are correctly positioned. Even though the rails are loosely mounted in the brackets, a small angular misalignment of the brackets (leading to rails which are not parallel or skewed to one side) can result in blind creasing or jamming. The problem is exacerbated in such blind systems for apertures with a high aspect ratio. A novel bracket for preventing such misalignment was proposed in WO 2009/098433. However, the success of the system relied upon careful installation by an experienced workman, so it did not lend itself to the mass DIY market. Accordingly, the present invention has been devised with a view to addressing or at least ameliorating this problem in a more user friendly way.